Expired
Lead Plaintiff Deadline
Apr 6, 2026
Please Upload related files below
Fill in below.
Tell us the stocks you own using SnapTrade, and we will keep you informed about class action litigation related to your stocks. We monitor critical case developments that may affect the price of your shares and your possible monetary recovery. SnapTrade only shares the tickers you own and your transaction history, not your account numbers. Using SnapTrade and participating in our monitoring service is free and does not create any attorney-client relationship or obligation on your part.
Don’t miss out on possible monetary recovery - link your brokerage account with SnapTrade.
According to the complaint, defendants provided overwhelmingly positive statements to investors while, at the same time, disseminating materially false and misleading statements and/or concealing material adverse facts concerning the true state of setrusumab’s potential and the true risk inherent in the study protocols put forth; notably, that, while setrusumab does increase material bone density, this increase does not correlate to a decrease in annualized fracture rates or otherwise the Phase III Orbit and Cosmic studies were much less likely to be able to demonstrate such a link than management claimed. On December 29, 2025, Ultragenyx announced that both its Phase III Orbit and Cosmic Studies had not “achieved statistical significance against the primary endpoints of reduction in annualized clinical fracture rate compared to placebo or bisphosphonates, respectively.” The Company attributed the study failure to a “low fracture rate in the placebo group” of Orbit and a trend that fell shy of statistical significance in Cosmic. Following this news, the price of Ultragenyx’s common stock declined dramatically. From a closing market price of $34.19 per share on December 26, 2025, Ultragenyx’s stock price fell to $19.72 per share on December 29, 2025, a decline of about 42.32% in the span of just a single day.
In order to be eligible to join the RARE class action lawsuit, you must have incurred a loss on shares of Ultragenyx purchased during the class period listed above.
If you suffered a loss in Ultragenyx during the relevant time frame or pursuant to the relevant offering(s), you have until April 6, 2026 to request that the Court appoint you as lead plaintiff. Your ability to share in any recovery doesn't require that you serve as a lead plaintiff.
A federal securities fraud class action, under the Securities Exchange Act of 1934, including Section 10(b) and Rule 10b-5 has been filed against Ultragenyx Pharmaceutical Inc. (NASDAQ: RARE) in the Northern District of California. The proposed class covers investors who acquired Ultragenyx common stock, traded on the NASDAQ under ticker RARE, between August 3, 2023 and December 26, 2025, inclusive.
According to the complaint, investors allege the company and senior executives repeatedly touted setrusumab (UX143) for Osteogenesis Imperfecta, claiming strong bone mineral density gains, a secondary endpoint, would translate into fewer fractures and that the Phase III Orbit and Cosmic randomized, double-blind, placebo-controlled study designs would reliably show that effect. The truth emerged when the company later disclosed that the Phase III studies failed to achieve statistical significance on their primary fracture-reduction endpoints (annualized clinical fracture rate reduction), and management acknowledged uncertainty about the data. Investors experienced sharp stock declines following the corrective disclosures.
“Most RARE shareholders never file or join the class action, which means they miss out on potential recovery funds,” said Attorney Joseph Levi.
Case Name: Bailey v. Ultragenyx Pharmaceutical Inc. et al.
Case No.: 3:26-cv-01097
Jurisdiction: U.S. District Court, Northern District of California
Filed on: February 4, 2026
Ultragenyx is a biopharmaceutical company, a Delaware corporation headquartered in California focused on rare and ultrarare genetic disorders (orphan diseases), with product candidates typically in-licensed from partners or academic institutions, and it develops gene therapies using a proprietary HeLa cell manufacturing platform. One key program during the period was setrusumab (UX143), a drug that targets bone metabolism for Osteogenesis Imperfecta.
August 3, 2023-December 26, 2025, inclusive.
All investors who purchased or otherwise acquired Ultragenyx common stock, ticker RARE, during the Class Period may be eligible to join the Ultragenyx Pharmaceutical Inc. (RARE) class action lawsuit.
The complaint names Ultragenyx, Founder/President/CEO/Director Emil D. Kakkis, and Chief Medical Officer/EVP Eric Crombez. Investors allege these defendants promoted setrusumab's prospects in the Phase III Orbit and Cosmic studies by linking early bone mineral density gains to expected reductions in fracture rates and by expressing confidence in study design and control of variability, in violation of the Securities Exchange Act of 1934, including Section 10(b) and Rule 10b-5.
The narrative begins on August 3, 2023, when CEO Emil Kakkis told investors on an earnings call that the bone mineral density increases, a secondary endpoint seen at three months were "sufficient enough to improve the strength of bones" and would "translate into fracture improvements." He followed on May 2, 2024, stating on another earnings call, "I really don't see any uncontrolled factors," signaling strong control over study variables. On August 1, 2024, Kakkis said the effect was "very large" and that he felt "pretty confident" stronger bones would compensate for activity changes in patients.
That tone continued into November 5, 2024, when Kakkis discussed powering assumptions, citing an assumed 50% reduction in the annualized clinical fracture rate and suggesting results closer to 67%, concluding they felt "pretty comfortable" with the study design. On August 5, 2025, he again assured investors that, based on Phase II data, even though the Phase II predecessor studies lacked a placebo control, UX143 would be a "transformational treatment" for pediatric and adult patients with Osteogenesis Imperfecta.
Meanwhile, the complaint alleges that these positive statements concealed material adverse facts: while setrusumab increased bone mineral density, that increase did not correlate to a reduction in annualized fracture rates with statistical significance, and the Phase III Orbit and Cosmic studies, including the placebo-controlled Orbit study and the bisphosphonate-comparator Cosmic study were far less likely to demonstrate such a link than management claimed. Investors allege defendants created the false impression they had reliable information pointing to Phase III success and minimized risks from study variability and from the clinical endpoint's sensitivity to low placebo-group fracture rates, artificially inflating the stock price during the class period.
The story turned on July 9, 2025, when Ultragenyx issued a press release stating the randomized, placebo-controlled, double-blind Phase 3 portion of the Orbit study (with a primary endpoint of annualized clinical fracture rate reduction) was progressing toward a final analysis around year-end. According to the complaint, this revealed the study had not achieved a second interim analysis that prior confidence had led investors to expect.
The full picture arrived on December 29, 2025, when Ultragenyx filed a Form 8-K with the Securities and Exchange Commission announcing that both Phase III Orbit and pediatric Cosmic studies failed to achieve statistical significance on their primary endpoints of reducing annualized clinical fracture rates versus placebo or bisphosphonates. Management attributed the outcome in part to a low fracture rate in the Orbit placebo group and conceded that bone mineral density changes, a secondary endpoint, were not accompanied by corresponding fracture reductions. On January 12, 2026, CEO Emil Kakkis added that the company needed to understand "why it is the way it is," noting long bone results did not appear better to a statistically significant degree and questioning whether increased activity or other factors explained the fractures.
The market reacted swiftly as disclosures unfolded. From a closing price of $41.44 per share on July 9, 2025, Ultragenyx fell to $31.03 on July 10, 2025, a one-day decline of $10.41 or about 25.12% after investors learned the Phase 3 Orbit study had not achieved the expected second interim analysis and was moving to a year-end final analysis, as the market digested a corrective disclosure and artificial inflation dissipated. The selloff deepened when the company disclosed the Phase III failures.
From a closing price of $34.19 per share on December 26, 2025, Ultragenyx fell to $19.72 on December 29, 2025, a one-day drop of $14.47 or approximately 42.32% as the market absorbed that neither Orbit nor Cosmic met the primary fracture-reduction endpoints, and investors suffered substantial losses.
The Court will issue its order for lead plaintiff and counsel in the weeks after submissions are due.
The Court will then consider motion for class certification.
The Court will later consider a motion to dismiss.
Disclaimer: This shareholder alert is for informational purposes only and does not constitutelegal advice. Consult a qualified attorney for personalized guidance. No specific outcomes are guaranteed.
TOP